Russian opposition leader Alexei Navalny, who was arrested during anti-government protests, has been released without charge, his lawyer said.

Mr Navalny was arrested after a brief appearance at rally in Moscow demonstrating against Vladimir Putin and calling for a boycott of the March presidential election that he said would be rigged.

His lawyer, Olga Mikhailova, told Reuters that her client had been released without charge but would have to face court at a later date.

If charged with violating laws on holding demonstrations, Mr Navalny could face up to 30 days in jail.

Mr Navalny,41, who has been barred from running in the election and whose office was raided by police on Sunday morning, urged his backers to continue to demonstrate despite being detained.

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Video:Police detain Putin opposition leader

Mr Navalny's YouTube channel broadcast footage of police arriving in his office on Sunday morning, which authorities said was in response to a "bomb threat".

The opposition leader claims support for 65-year-old Mr Putin is exaggerated and artificially maintained by state media.

Mr Navalny has little chance of influencing the election which Mr Putin is expected to win comfortably but his ability to mobile crowds of mostly young people using social media has infuriated the Kremlin.

Video footage posted on social media showed Mr Navalny appear on Moscow's main thoroughfare, Tverskaya Street, a few hundred yards from the Kremlin where he joined several hundred supporters taking part in the protest, which the authorities had said was illegal.

He had only walked a short distance when he was surrounded by police officers wearing helmets who grabbed him to the ground on the pavement and then dragged him feet first into the patrol vehicle.

He was held at a police station in central Moscow for several hours before being released.

Mr Navalny, who says he has faced a campaign of harassment from the authorities, has struggled to mobilise the same numbers in the two nationwide protests he has called since he began mobilising demonstrations in June 2017.